More Power and Better Mileage

[Lin]

I just brought my 5a home on a 200+ mile run from Don's in Bakersfield.  There was a lot of work done on it, but the big three were switching to an Allison 647, upgrading the C60 injectors to N65's, and adding Jakes.  There is always some debate about the mpg cost of such changes, but from this short sample ride, it looks like I went from 7.66 to 7.96.  The difference would seem to be attributable to being able to use the extra power to run a gear higher a good deal of the time.  Even though 200+ miles is not a large sample, it did include the moderate mountain climbs and traveling between 60 and 70 most of the time.  I would be happier with 10 mpg but I won't be greedy.

On another issue, I did like having the 2-stage Jakes.  The first stage only adds a mild drag, but it was nice to just turn it on and be able to hold a steady speed coasting down some of the hills.  I would not say that Jakes are really necessary go east on Hwy 58 (they would be more valuable going the other way), but just knowing they were there if needed made it possible for me to descend a gear up than I would have if I only had the brakes to depend on.

Thanks to Don for these great improvements and for catching several things that were on the edge of failure too.

[DMoedave]

Lin, we were very surprised at our mpg avg after going to the Allison also. You probalby need to do some more miles for sure but sounds good so far! We only have the one stage Jakes, but they are nice. Sounds like a win  win more power more fun and you can always lay off the pedal. Or can you ha ha! Thats my new goal, try and lay off the bus's fun pedal more!

[Lin]

DM,

I am not looking to go really fast, but there are some roads that I would find painful to stay at 55.  For example, coming home on this trip involved a long, flat, straight run through the Mojave to Barstow.  When on roads like this the speedo tends to creep up.

[edvanland]

Lin
Do you have his phone number? I have some issues I would like addressed on my bus.  Not real sure who here in Arizona I can trust.
If you do please either post or send me a private e-mail at edvan@q.com.
Thanks
ED

[luvrbus]

Don's # 1-661-301-4648 he is traveling to San Antonio Texas for some testing on his engines



good luck

[edvanland]

Thanks Loverbus. Is this Christi?, we met in Quartzsite early this year.
ED

[Lin]

Clifford,

I spoke to Don yesterday, and he had not left yet.  He was still repairing the 6v that got dropped the last time it was shipped.  Those engines don't seem to take well to rolling.  I know he was getting ready for the trip though.

[luvrbus]

Ed,there is a good DD shop at Higley I have no idea if he still works on buses but give him a call


Baker Machinery 1-480-988-1187 he had some top notch 2 stroke guys for taking care of the mines in that area he has the best engine machine shop in the country does all of WW Williams work



good luck

[JohnEd]

Ed,

Always do what Clifford says. Always!

That being said, Don seems to be traveling through your neighborhood.  He is the kind of guy that will visit you if that is convenient.  He is in business though and if you take up very much of is time be prepared to pay for a bargain.  You might want his opinion to compare with the Clifford proposal.  Getting more info should not hurt and like I said....listen to Clifford.

John

[bevans6]

Is the Allison 647 behind an 8V-71N?  If so, what did Don say about the power/torque limits of the tranny?

I am contemplating the exact same swap, as my left knee gets worse and worse...

Brian

[Lin]

Brain,

Yes, I do have an 8v71N.  As I remember it (so it is probably a little off), Allison rated the 647 for around 980 ft/lbs of torque and 305hp.  The 644 was also close to that and would work since even though they call the 8v71 a 318, it isn't in our case.  Some would say that this means the transmission is working at close to the top of its range, but considering our type of general use and the fact that you are not likely to abuse it, it should be fine.  It may not really matter, but we used a Valvoline synthetic fluid in the hope that that will keep it cooler also.  The price is not much more than regular fluid.

[bevans6]

Thanks for that explanation.  Can I ask what is the difference between the 647 and the 644 or any other 640 series transmission?  Also what did you do for a shifter?

This is about exactly what I hope to end up with. 

Brian

[luvrbus]

Having done the 4 speed to auto on my MCI 5 and a friends years back a 6V92TA,740 and Stone/Bennett shifter would be my choice a lot easier to do set the 6v92 at 300 hp and drive on.
Those parts to do the swap get a little pricey I thought for a while I was part owner of AZ Transmission



good luck

[Lin]

Clifford has a real point.  The transition parts to join the 647 to the 8v71 are expensive unless you can find old ones, which is difficult.  The 740 would be a much stronger transmission too.  Of course, as everyone says, there is not enough room for an 8 behind the 740, so you have to go to a 6 and do a serious upgrade on your cooling.  I think that doing it the way we did is still less expensive though since we did not have to buy another engine, but it is not a sports car.  It seems that this will be good enough for me though.

As far as the shifter goes, we just used a Morse-type cable and shifter.  The pedestal is where the old stick was.  The 644 and 647 are heavier duty than the 640 or 643.  They use the same torque converter as the 740.  The 647 was an update on the 644.

If you want to keep your present engine and go to the 644/647, you might start shopping the parts now.  If you take your time, you might be able to get them reasonably.